Manufacture of motor fuel by alkylation with a light cracked naphtha



iIIg' isopar'a'ffin and strong surrune acid Patented Apr. 13, 1948 TUNITED stares "OFFICE- NAPHTH- ware ., a corporation or nea- KYLAIIQN WITH 'A LIGHT GRACK ED No Drawing. Ap'blication Aiiitii i943,

Serial No. 484,214

1 This nvention relates to the mant recture or motorfuels and. has to do particularly with a roc ss for improving cracked naphtha's by treatm th naphtha the pr sence or an amyiationcatalyst and an is paramn. unde suchc'ojn di tio'ns that the i'sopar affin is alkylaited by the unsaturated constituents of the naphtha; i

This is a eoh ti uauoa-m-pa t or our depend iiig application, Serial No. 295,0;58, filed Septembet-"1 5, i939, and now-abandoned. v

' it has been-proposed in S; Patent 1%. 2,260,- Q44= to treat cracked naphthas or cracked gasouses under amyranng conditi ns "1th fa alkylati'b'ri er the cesarean the ol V stituent's of the oil. In theti atfiier'i't er 'ci'ac ed gasoline and hablithas by this method, lie of the catalyst has been statement to interactiohffletvieen the catalyst and aromatic components or the 011'; Also alkylat'd a1;- ics of higher boiling range than sesame are formed whereby the yield 'of desired product. is reduced. It has now been. found that greatly provedcresults may :be obtained by treating a cracked naphtha fraction-or cut boiling below the boiling range of the ma ler portion of the aromatic constituents-under different and :critical conditions or isoparafiin to naphtha ratio and catalyst to naphtha ratio as hereinafter de= scribed.

The cracked naphtha or fractions of cracked gasoline, which may betrea-ted according to the invention; should preferably have an end boiling point not in excess of about 200 F. Suitable materials for treatment include fractions of :thermallyandcatalytically crackedgasolin'c, although it has been found that the low-boiling fractions .ofgasoline resulting from the catalytic cracking of oils constitute a superior charge stock over similar fractions from -a gasoline obtained by thermal cracking. Best results have been obtained by treating certain closely fractionated cuts, particularly a fraction comprised essentially of a mixture. of C5 and Ce hydrocarbons. It is contemplated, however, that fractions consisting'essentially of individual frac tionssuch-as C5, C6, and C7 hydrocarbons. or any mixture thereof maybe used. V In accordance with the invention, the products of thermal orcatalytic conversion of hydrocare bon. oil are fractionated. 'to separate *a light cracked. naphtha fraction, and the light riaph tha fraction istreated with low-boiling isoparaffins such'asrisobutane orisopentanepin an amount in excess :of the olefin content andipref- 11 Claims. (01. att cs ai) cond tions.

N e ystmfa'y bee. suitable "alkyl'ation catalyst "such 'as all y 7 chloride and anhydrous hydrogen chloride, boron trifluoride and, water Edblek, and preferably strong sulfuri c shi be L t to for example about 94 t'c 98% 564, The conditions for alkylation involve teiii tures of about 0 to 100 F., liquid phase, intimate contact between the hydroear bons and catalyst; a volume r'atio of catalyst to riaphthalof about /221 to 2:1 orag-r'eater, anda time of contact of about *5 to se mix-iute's;

In practicing the invention, there is prepared a naphtha fraction suitable for treatment which, for example, may be obta" ed from cracked naphtha fconversiori productslby fra'ctiona'l distillation. The fraction, with or Without additional treatmentsuch ais caustic Wash or desulfurization, is treated with an alkylation catalyst, such as 98% sulfuric acid mine presence one large excess of low-boiling isoparaflins, such as isobutane. flhe naphtha is 'preferably introduced into a miirtme cjon'taining the isoparaiffin and the catalyst, under such conditions that the ratio of :isoparafilr to olefins is fairly high at all times, The treated naphtha containing the alkylate i'ss'eparafted from the catalyst, caustic washed, and after rfractiohation and stabilization may be used for the manufacture of motor According mo one :method ofioperation, cracked naphtha conversiongproducts :are separated by fractional: distillation1rintoa highboiling naphthe fraction 'and -a IOW-bbj'ling naphtha fraction. It hasrbeen,=found that alow-boiling cut usually amounting to about 15 ;to ;50 of an ordinary cracked :aasoline; is substa-n ially free irom arom'atics. The low-boiling-fraction is then alkylatednwith the :isoparafiin w-to ;plj0.duce a high yield of iiigh-?anti-jknock producti: suitable for the man- .ufa'cture of motor fuel; and :mayadvantageously be.:reblended =wiithithe high-boiling fraction.

.The: reactions aremot fully understood and. the invention is, mot tpredicated on any theory of reaction; There appears totbexalkylation of the iso'paraffin bytheolefills in the cracked naphtha to iform high-.antiiaknock saturated bran'ch chain hydrocarbons ofwthe ygas oline b'oiling point range. The' reaction is also 'gaiccompa'nied by "a substan- .tial reduction rirr su-lfur content and improve ment :in color :andcgum stability 10f the treated .Zprodu'ct. =A1so-,; theqleadsusceptibility; that is,

Example I Hydrocarbon oil was thermally, converted in conventional manner in a Holmes-Manley cracking unit at cracking temperatures and pressures to reduce a substantial proportion thereof to hydrocarbon products within the gasoline boiling.

range. The conversion products were fractionated to separate a. light C5-C7 cracked naphtha fraction having a boiling range of -95-1'96 F. and a heavier cracked naphtha, fraction having a boiling range of 197-397 F. The said light fraction contained 41.8% by weight of olefins,

and amounted to about 31% by volume of the total cracked naphtha boiling between 95 F. and 297 F. Portions of the said light fraction were then treated with strong sulfuric acid with and without the presence of added isobutane under the conditions and with the results as set forth in the following table:

' t'lllreated in t'tlxreaitzJed in epresence e a sence Untreated of added of added isobutane isobutane Isobutane to naphtha, volnrne ratio .4 3:1 Reaction time, minutes. 150 120 Tem erature, F 71 67 Acid, per cent H2804.-. 97 97 Ratio of acidgto gasoline, volume ratio 0. 67:1 0. 75:1 Yield of 400 end point gaso- 1ine-basis weight 200 end point charge .per cent 105 63.7 Total yield butane-free liquid-basis 200 end point charge, per cent by weight per cent.- 110 75. 2 Concentration of recovered acid, per cent H2804 92. 4

Tests on Gasoline Color +25 +30 +30 Sulfur, per cent 0. 017 0. 005 0. 013 Bromine Number 83 l Voorhees-Eisinger Induction est 17+ hrs. 22+ hrs. 195 rmns. Octane Number, CFRM 75. 2 75.2 60. 5 Octane number, plus 1 cc. tetraethyl lead 78. 3 86. 9 7l. 4 Initial Boiling Point 95 110 99 End Point 196 356. 392

From the above results, it will be observed that without the addition of isobutane only 63.7% of the charging material was recovered as gasoline, whereas with a 3:1 ratio of isobutane to gasoline the yield was 105%. Without any treatment, the untreated gasoline with 1 cc. of added tetraethyl lead per gallon is improved only from 75.2 to 78.3'octane number. Although the susceptibility to lead is improved by simple acid treatment, the base octane number was lower. Thus, the octane number was 60.5, and with 1 cc. tetraethyl lead per gallon, the octane number was 71.4. With a 3:1 isobutane-to-gasoline ratio, the octane numher was 75.5 and the lead susceptibility is very good; thus, 1 cc. of tetraethyl lead per gallon gave an octane rating of 86.9. The acid treatment alone lowers the sulfur content from 0.017 in the charge gasoline to 0.013 in the treated product. With a 3:1 isobutane-to-gasoline ratio, however, the sulfur content was reduced to 0.005%. The induction test shows 195 minutes for the acid-treated charge in comparison with over 17 hours for the untreated charge stock, and

over 22 hours for the product treated with 3:1 isobutane-to-gasoline ratio.

Another portion of the same 95-196 F. cut of cracked gasoline was treated under essentially 5 similar conditions as set forth above in the middle column of the table, except that a lower iso- .butane-to-naphtha ratio of about 1:1 was employed, as shown in the following table:

Isobutane/naphtha vol. ratio 1:1 Reaction timemin 240 Temperature, F 68 Acid H2504, 96.6

Acid/gasoline vol. ratio 0.67:1 Yield of 400 end point gasoline basis naphtha charged, by wt 92.6 Octane number"CFRM 72.9 Bromine number 3 Comparing these results with the middle column of the first table, it will be seen that the lower isobutane-to-naphtha volume ratio of 1:1 gave a substantially reduced yield of 400 F. end point gasoline of lower octane and higher bromine number than when a substantial volume 25 excess of isobutane tonaphtha was employed.

Still another portion of the same 95196 F. cut of cracked gasoline was treated under essentially similar conditions as set forth in the middle column of the first table, except that a 3 lower volume ratio of acid to naphtha of 0.33:1 was employed, as shown in the following table:

Isobutane/naphtha vol. ratio j 2:1 Reaction time-min 150' Temperature, F 72 Acid H2804 97 Acid/gasoline vol. ratio "0.33:1 Total yield debutanized gasoline basis j naphtha charged, by wt 100 40 Concentration of recovered acid- H2SO4 87.7

A C5C6 cut of catalytically cracked gasoline containing 83.7% by weight of olefins and a heavier naphtha fraction were separated by tractionation from conversion constituents obtained by the catalytic cracking of gas oil in the presence of a silica-alumina type catalyst, This catalytic cracking was carried out in well-known manner by passing the gas oil to be converted through a to cracking zone containing an active cracking catalyst and maintained at active cracking tempera.- ture, such as about 900-1000 F., keepin the oil in contact with said cracking catalyst within said cracking zone for a period suflicient to con- 65 vert a substantial portion of said oil into motor fuel constituents. The fractionation of the cracked products described above separated a light naphtha fraction having a boiling range of 81-157 F. and which was substantially free of aromatic constituents and contained a substantial amount of olefinic constituents having a. high acid heat. The said light naphtha fraction con- -tained substantially equal proportionsof Cs and C6 hydrocarbons. The said fraction so segregated was then passed in a mixturewith isoparafilns in product having. a high octane numberlead response as above described. The conditions of operation and theresiilts obtained in this run are I setforth in the following table:

Isobutane to naphtha wtfratio 3: 1 rtea'ctiiir time-min. 90 filPiallH fB;'F. 173 acre nis'on 98 Acid/gasoline. ratio 3:1 Afcifdlfgas'oline vol.'i atio 1.2:1 (approx) ine above res lts. sho that the. light catalytia daily-cr cked naphtha fraction constitutes a superior'charge stool; over a, similar fraction of th'rmally=cracked naphtha for purposes of the present invention. 7 Alkylate formed from the light fraction may be c'oirilc'iined with the heavy naphtha'fi'action separated in the fractionation of the products or the eatalytic cracking treatment as above desci'ibed,' to thereby'form a gasoline blend'containl'ng light naphtha alkylate and heavy catalytically-cracked naphtha.

Example III A portion of the heavy fraction oi catalyticallycracked naphthairom whichthe GCe cut'had been removed (Example-II above), was further trac'tionalted toseparate a 0 1 out containing 73.6 by" weight of olefinsand :havmg a boiling range of 158-207 F. This C1 cut was then alkylated under the conditions and. with the results set forth in the following table:

'- all -F endiiomtdbzitttnized alkylate %,yie1 ;te s orcienn chareedn 101.5; Theabcye results indicate that this fraction is not as good a charge ,stock as th Cs-eGeiracti0n,;and that the G7 const tue ts e abou t highest boilingqcr-acked naphtha materials that cancbealkylated in accordance with the present invention -with the advantageous results and low catalyst onsumption. as ab v descr Thcprocess .oirthfi present invention is an effectlye..method of desuliurizing hydrocarbons and; may. .advantageous ly be applied to the amylation; oi a lows-boiling fraction derived tra n; a stock of high, su1furcontent. 7

illustrated by the examples set forth above, the present invention enables cracked" naphthas tobe .mar-kedlyimproved in lead response and other=properties, rendering them eminently. suitable for. high anti-knock motor fuels, suchfas base stock for. the manufacture of aviation, gasoline. As distinguished irom conventional acidtreating, this is accomplished without doss in yieldgand, in; most instances; with an; appreciable increase in yield. Moreoveryby the usewci' the 'operatingqconditions set iorth above. including,

a substantial volume excess of isoparaifin or iso-v butane to, naphtha, and a volume ratio; or c-ata lyst to naphtha of about 0.511; tozlficli and higher,

a substantially saturated product issobtainedvwith marked reduction: and. economy in: catalyst consumption. l I

. Obviously many modifications and variations of the invention, as, hereinbefore set forth. may be made without depatring. from the spiritwand scope. thereof, and thereforepnly i'such, limitations s-hould :be imposedjas areindi-cated. in the appended claims.

t We claim: l-aThe method. in the manuiacture. chino tor fuel hydrocarbons. which "comprisescraching hydrocarbon oil under conversionconditions oia perature and pressure to reducemal substantial proportion of the OilztO hydrocarbonswithinthe gasoline. boiling range, fractionatin'g, the conversion. products to separatena l-i'ght normally liquid cracked naphtha fraction. and. a,. ln'gher boiling cracked naphtha fraction, *thesaid li'ght. naphtha fraction having an end boiling pointnot imexcess. of-ab'out 1200? F; and. containing a substantial proportion of olefins but being, subst'anti-ally tree from aromatics, subiectingrtihesaid. light. naphtha fractiontocontact inxliquidphasewith a; volume substantial excess o1? the volume *of naphtha being treated of a low-boiling isoparafiin selected from the group consisting of isobutane and isopentane in the presence of a volume ratio of active alkylation catalyst to naphtha of at least about 0.521 in a reaction zone maintained under alkylating conditions, whereby isoparafiin is alkylated by the olefins of said light cracked naphtha fraction, and recovering from the'alkylation reaction products a substantially saturated gasoline fraction of broader boiling range than that of the said light cracked naphtha fraction prior to the alkylating step.

2. The method according to claim 1, wherein the said light cracked naphtha fraction is a C5Ce cut.

3. The method according to claim 1, wherein the low-boiling isoparafiin is isobutane.

4. The method according to claim 1, wherein the alkylation catalyst is strong H2504 of alkylation strength.

5. The method according to claim 1, wherein at least a portion ofthe said substantiallysaturated gasoline produced in the alkylation of the light cracked "naphtha fraction is blended with at least a portion of the said higher boiling cracked naphtha fraction. V l a,

6. The method according to claim 1,'wherein the cracking of the hydrocarbon oil is carried out in the presence of an active cracking cata-- lyst under catalytic crackingconditions.

7. The method in the manufacture of an improved motor fuel which comprises'fractionating a cracked naphtha charge to separate a light normally liquid cracked naphtha fraction and a heavier cracked naphtha fraction, the said light cracked naphtha fraction being substantially free of aromatic constituents and containing a substantial amount of'olefinicconstituents and being of too narrow boiling range to constitute a balanced motor fuel, reacting the said light cracked naphtha fraction with added isobutane in such proportion that the molar ratio of isohutane to olefinic constituents is not less than 1:1 in contact with an active alkylation catalyst under alkylating conditions, whereby isobutane is alkylated by said olefinic constitucuts, and recovering from the alkylation reaction products a substantially saturated gasoline hydrocarbon fraction of broader boiling range suitable for motor fuel. i

8. The method according to claim '7, wherein at least a portion of the said substantially saturated gasoline hydrocarbon fraction of broader boiling range is blended with atleast a portion of the said heavier cracked naphtha fraction to produce the improved motor fuel; a V I r 9. The method according to claim 7, wherein the cracked naphtha charge is'a catalytically cracked naphtha. V

10. A method of producing gasoline having a low acid heat, high octane number lead response by conversion of higher boiling hydrocarbons which comprises passing the oil to be converted through a cracking zone containing an active cracking catalyst and maintained at cracking temperature, keeping said oil in contact with said cracking catalyst within said cracking zone for a period sufficient to convert a substantial portion of said oil into motor fuel constituents, thereafter separating from the cracked products a light naphtha fraction substantially free of arcmatic constituents and containing a substantial amount of olefinic constituents having a high acid heat, passing thefraction so segregated in a mixture with isoparaflins in such proportion that theomolar ratio of isoparaflins :toolefinic constituents is not less thanv one to-one in contact with an; active alkylating, catalyst capable of accelerating. .thcunion between isoparafiins and tolefins to form acsaturated product and maintaining said mixture .in contact with said catalystfor a'period sufiicient to alkylatea substantial amount of said olefins in said light naphtha fraction and to increase the boiling range thereof. 7

ll. A process for the conversion of hydrocarbon oils to form gasoline havinga'low acid heat, high octane number. and lead response. which comprises passing the oil tobe converted through a cracking zone maintained at:active cracking temperature, contacting said-oil'rwithin said cracking zone while at active cracking temperature with a cracking catalyst, -keeping said oil in contact with said catalyst' for a period sufiicient to convert a'substa'ntial portion thereof into gasoline constituents, thereafter separating a light naphtha fraction] substantially. free a of aromatic constituents and containing a relatively with said olefinsrto form-a saturatedalkylate product and thereafter" combining alkylate formed from said last-named a-lkylating treatmentfwitl'i heavynap'htha from said catalytic cracking treatmentto form a gasoline blend con taining light naphtha alkylate and heavy catalytically cracked naphtha. I l

1 ARTHUR R." GOLDSBY,

v H 7 ou s A; CLARK. "REFERENCES CITED:

following references are, of record in the file of this patent e w V UNITED STATES PATENTS Number v Name Date r 2,172,560; Kempet al. Sept; 12, 1939 2,211,747 Goldsby et al. Apr. 13, 1940 2,341,48'7m Taylor et al. Feb 8, 1944 2, 99,240], Mc Allist er etal. *Apr. 30;19'i6 

